The problems of sensorimotor coordination do not lend themselves readily to conventional computer analysis. It is well known that many functions performed readily by the human brain are difficult to perform by computer, such as recognition of patterns which vary within certain limits, e.g., recognition of signatures or faces. The complex features of sensorimotor coordination have proven especially difficult to control by conventional means.
A major distinction of the present invention from conventional computers lies in the fact that the latter employ mathematical operations based upon the logic of Boolean algebra. The present invention, by contrast, employes geometrical operations as its basic function. The class of information processors embodied in the present invention is not computational, but geometric.
In order to distinguish the devices of the present invention from prior art computers, new terminology is employed. The basic device, which is termed a Cognitor, processes multivariant inputs from sensory elements and coordinates a multivariant output effector system. The Cognitor operates as a geometrical processor that handles information, expressed in terms of vectors, using oblique systems of coordinates. A related device, applying the Cognitor processing system to sensorimotor control with space-time coordination, is termed a Coorditor. The Coorditor incorporates additional processing elements to accomplish specific space-time coordination. Thus the Coorditor is applicable in situations where a time delay in the sensory or effector systems requires additional extrapolation (termed herein "lookahead"), to coordinate output motions with motions of the external world.
The present invention was achieved by studies on the nature of brain function. Progress in modeling the principles of brain function has been hampered by a widespread fallacy that the algebraic logic of computers and the information processing of the brain were fundamentally analogous. However, two information processors in the prior art represent intermediary stages between conventional computers and the present invention. These are the Perceptron (Rosenblatt, U.S. Pat. No. 3,287,649) and the Nestor Module (Cooper et al, U.S. Pat. No. 3,950,733). Both information processors are based upon vectorial processing operations. In contrast, a main feature of the present invention lies in the fact that its operating principle (and, in consequence, its operating hardware) necessitates a distinction between covariant and contravariant vectors, a distiction absent in the prior art.
A central concept herein is the idea of coordination. As understood from the field of brain function studies, coordination is achieved when the multivariant sensory input information from the external world is processed in such a way that multiple effectors are activated in a concerted manner to achieve a desired action with respect to the external world. For example, a tennis player tracking the flight of the ball coordinates the concerted action of his muscles to intercept the ball at the desired time and in the desired manner. The devices of the present invention function to coordinate such sensor inputs and motor effector outputs, and are therefore termed sensorimotor coordinating devices. It will be understood that the terms "sensory" and "motor" are not limited to a biological context, but are intended to include any sort of informational input, e.g., electromagnetic radiation, acoustic vibration, magnetic and thermal variations, etc., and any sort of effector output, e.g., electrical, mechanical, pneumatic, acoustical, etc., respectively.
It is of fundamental importance, that in the Cognitor systems vectorial variables are mathematically expressed in oblique frames of reference; where the angles between the coordinate axes are usually not right angles. It is known that in a non-orthogonal system of coordinates a vector is either covariant or contravariant. The Cognitor systems can be recognized formally by the fact that they distinguish between two kinds of vectors. Using oblique systems of coordinates it is not sufficient to deal with vectorial quantities without explicitly distinguishing between the two possible kinds, since not only their components are numerically different but there is also a fundamental difference between the processes by which they are established, as well as profound differences in their ultimate usefulness in application.
In the Cognitor and Coorditor systems, covariant and contravariant vectors are transformed from one to the other. Covariant-contravariant transformations can be accomplished by any of several known means. It is convenient to employ a metric tensor to accomplish such transformations. It is well established in tensor analysis that if the geometry of an abstract mathematical space is determined by a metric tensor, then all properties of the affine space are formally expressible (e.g., distances of points, angles between lines in the space, movements along geodesic lines, etc.). Although geometrical properties are elegantly and concisely handled by tensor analysis, the present invention lies not in the use of the particular method of tensor analysis, but the utilization and development of a paradigm of coordinated control using the concept of multidimensional geometric transformations, expressed in oblique systems of coordinates. Thus, the key for separating the prior art from this invention is whether there is a distinction expressed between the two kinds of vectors. While in tensor analysis these are normally called covariant and contravariant vectors, it will be understood that other terms representing the same concept, such as orthogonal projections and parallelogram components, etc., are deemed equivalent.
The other significant feature of this invention is that it utilizes the understanding of the functioning of specific brain regions for the design of non-biological devices. In this case, this part is the cerebellum, which is the best known region of the brain, regarding both its structure and its function. Accordingly, throughout the past two decades a great deal of effort has been made in understanding the function of this organ with the expectation in mind that brain research would eventually yield not only an understanding of how a part of the brain works, but also of how such knowledge could be put into practical use. The invention is a result of the realization that the cerebellum achieves the task of motor coordination via a covariant-contravariant vector-transformation; that is, the cerebellum serves as a space-time metric tensor. It is already possible to determine some characteristic features of the class of device that could be built upon this understanding. This constitutes the Coorditor space-time coordinator device.